1. Field of the Invention
The present invention relates to a speaker, more particularly to a speaker having a magnetic member installed on its diaphragm.
2. Description of the Related Art
A conventional cone-shaped speaker 10 construction is shown in FIG. 1, which comprises a metal frame 11 in the periphery, a recessed resonant space 12 in the center enclosed by the metal frame 11, a diaphragm 13 enclosed by the metal frame 11 being recessed on top of the resonant space 12, a slidable sleeve 14 having one end connected to the center of diaphragm 13, a winding, 15 wound around the other end of sleeve 14, a circular corrugated damping film 16 around the sleeve 14 between the diaphragm 13 and winding 15, the damping film 16 being extended radially such that the outer circumference thereof is engaged with the metal frame 11 in a predetermined position within the resonant space 12, an opening 17 on the central bottom portion of metal frame 11, a seat 18 connected to the periphery of opening 17, a first through hole 19 corresponding to adjacent opening 17 on the top side of seat 18 such that the portion of sleeve 14 having winding 15 wound thereon may insert into seat 18 through the bores of opening 17 and first through hole 19, a second through hole 20 on the bottom side of seat 18, a metal core 21 with a T-shaped cross-section having the vertical portion (i.e., post) 211 passed through the second through hole 20 and the bore of the portion of sleeve 14 having winding 15 wound thereon, and a permanent magnet 22 wound around the seat 18. The cross-sectional view of the above mentioned conventional speaker 10 is further shown in FIG. 2. The winding 15 is excited to generate an electromagnetic effect when an electric current is flowed through. Then first magnetic lines are generated in the winding 15. Also, second magnetic lines are generated in the permanent magnet 22. Such first and second magnetic lines co-act each other to create a continuous attraction-repulsion effect. As such, the sleeve 14 having winding 15 wound thereon may slide vertically as magnitude and direction of current applied thereon being changed. In turn, the diaphragm 13 is vibrated to generate sound for outputting through speaker 10.
The seat 18, core 21, and permanent magnet 22 of the conventional speaker 10 are bulky and mounted on the side of metal frame 11 opposite the diaphragm 13, thus inhibiting the further reduction of speaker size especially the thickness thereof. The portion of sleeve 14 having winding 15 wound thereon is inserted into the seat 18 sandwiched between the limited gap between the post 211 of core 21 and the permanent magnet 22. This increases the difficulty in assembly. Also, a not precisely maintained gap may adversely affect the quality of speaker 10. The position of core 21 around the seat 18 restricts the travel of sleeve 14. As such, the portion of sleeve 14 having winding 15 wound thereon may collide core 21 when speaker 10 outputs high-power low-frequency sound waves. Such collision may deform sleeve 14 after a predetermined time of use, thereby degrading the output sound quality of speaker 10. Such problems not only make the traditional speaker 10 unable to significantly reduce its size, but also make the breakthrough of the bottleneck on the design for the quality and volume of output sound very difficult.
In view of the above description about the shortcomings of the prior art, the present inventor has disclosed a speaker 30 in his U.S. Pat. No. 6,415,037, as referring to FIG. 2. The speaker 30 comprises a metal frame 31 in the periphery, a diaphragm 32 enclosed by the peripheral frame 31, a resonant space 33 in the center enclosed by frame 31 and diaphragm 32, a winding 34 installed to the inner side of the center of the frame 31 and a resonant space 33 on the center, wherein the winding 34 is excited to generate magnetic lines in the center when an electric current is flowed through. Then a continuous attraction-repulsion effect is generated in the magnetic member 35 corresponding to the winding 34. In turn, the diaphragm 32 is vibrated to generate sound for outputting through the speaker 30.
According to the speaker 30 disclosed in the U.S. Pat. No. 6,415,037, since the magnetic member 35 is directly or indirectly fixed on the center of the diaphragm 32 such that the space occupied by the seat 18, the core 21 and the permanent magnet 22 on the conventional speaker 10 as shown in FIG. 1 can be effectively reduced, thereby significantly reducing the thickness and the weight of the speaker. In addition, since the speaker 30 disclosed in the U.S. Pat. No. 6,415,037 has a winding 34 fixed and installed on a frame 31 corresponding to the inner side of the center of the diaphragm 32, therefore, when the winding 34 is excited, it creates an attraction-repulsion effect directly on the magnetic member 35 and drives the diaphragm to vibrate and generate sound. Such arrangement thus can effectively simplify the structure of the speaker, lower the cost, increase the travel of the diaphragm, prevent distortion, significantly enhance the low-frequency characteristics, and increase the power in order to break through the bottleneck of the design of the conventional speaker.